The Impact of Primary Care Clinician Staffing Mix on Quality

Huang PY, Yano EM, Lee ML, Rubenstein LV. The Impact of Primary Care Clinician Staffing Mix on Quality. Paper presented at: AcademyHealth Annual Research Meeting; 2002 Jun 1; Washington, DC.

Research Objective: Managed care organizations, including the VA, increasingly employ nurse practitioners (NPs) and physician assistants (PAs) in addition to physicians (MDs) as primary care (PC) providers. Research shows that non-physician clinicians (NP/PAs) provide high quality PC, but these studies evaluated NP/PA care for specific patients under specific practice conditions. This study examines the impact of increasing the NP/PA-to-MD staffing ratio on the quality of primary care.Study Design: We surveyed the PC practice leaders of all 170 VA medical centers (VAMC) in 1999 (94% response rate). We used survey and VA computer administrative data to measure facility characteristics (e.g., facility complexity, academic affiliation) and PC practice characteristics (e.g., firm system practice arrangement, use of managed care arrangements such as guidelines and provider education). Survey data for each VAMC was linked to 1999 PC practice outcomes as measured by performance measures for patient satisfaction, preventive care, and chronic disease management. The VA calculates performance measures yearly based on randomly selected patients visiting PC through: (1) the VHA National Ambulatory Care Survey, a national VA patient satisfaction survey, and (2) the Prevention Index (PI) and Chronic Disease Index (CDI), from the chart-based VHA External Peer Review Program. The NP/PA-to-MD ratio for each facility was calculated by dividing the number of PC NP/PAs by the number of PC MDs. We transformed the NP/PA-to-MD ratio and dependent variables (practice outcomes), and performed multivariate regression to predict the influence of the NP/PA-to-MD ratio on practice outcomes, adjusting for facility and PC practice characteristics.Population Studied: VAMC primary care practicesPrincipal Findings: Overall, 96% of VAMC PC practices reported using NP/PAs as PC providers; mean NP/PA-to-MD ratio 0.75. Academic VAMCs, practices with PC training programs, or with more provider education had higher NP/PA-to-MD ratios. In bivariate regressions, a higher NP/PA-to-MD ratio was associated with worse PI and CDI scores, but better patients' ratings of emotional support (p < 0.05). After controlling for facility and practice characteristics, a higher NP/PA-to-MD ratio remained independently associated with lower PI and CDI scores and greater patient satisfaction with emotional support (p < 0.05).Conclusions: VA PC practices with higher NP/PA-to-MD staffing ratios achieved greater patient satisfaction with emotional support. However, contrary to expectations, practices with higher NP/PA-to-MD staffing ratios performed worse than those with lower ratios on measures of preventive and chronic disease care. Future research should investigate whether the lower PI/CDI scores reflect problems with NP/PA roles within these PC practices (e.g., insufficient visit duration, excessive patient complexity) or whether they reflect overall structural deficiencies affecting the quality of both MD and NP/PA clinical work.Implications for Policy, Delivery or Practice: Despite research showing that NP/PAs perform especially well at preventive care, our results suggest that PC practices cannot be assured of improved preventive care merely by employing a higher proportion of NP/PAs in their PC clinician staffing mix. Policies directed toward encouraging increased hiring of NP/PAs in PC practices should be grounded in a better understanding of the optimal roles, relationships, and responsibilities of different types of clinicians within PC practices. Without this knowledge, the potential benefit of NP/PAs as a means to improve PC practice will not be achieved.Primary Funding Source: VA